Comment 2 for bug 324166

It was quite a long time ago, but I think that I just opened the file
with Python - something like:

sudo python
f = open('/dev/something', 'rw+')
f.seek(somewhere)
s = f.read(512)
f.seek(0)
f.write(s)
f.close()

I'm writing this to illustrate what I think I did - so please check
before you do something.